s3 vfs: Add a destructor to the fsp extension data API

I'm not certain if the dummy pointer is needed in struct vfs_fsp_data,
but I added it to be consistent with the comment below.

8 files changed, 20 insertions, 9 deletions

diff --git a/source3/include/proto.h b/source3/include/proto.h
index e5dbe60e11..1a1f8bef69 100644
--- a/source3/include/proto.h
+++ b/source3/include/proto.h
@@ -7317,7 +7317,9 @@ void sys_utmp_claim(const char *username, const char *hostname,
 
 NTSTATUS smb_register_vfs(int version, const char *name, const vfs_op_tuple *vfs_op_tuples);
 bool vfs_init_custom(connection_struct *conn, const char *vfs_object);
-void *vfs_add_fsp_extension_notype(vfs_handle_struct *handle, files_struct *fsp, size_t ext_size);
+void *vfs_add_fsp_extension_notype(vfs_handle_struct *handle,
+				   files_struct *fsp, size_t ext_size,
+				   void (*destroy_fn)(void *p_data));
 void vfs_remove_fsp_extension(vfs_handle_struct *handle, files_struct *fsp);
 void *vfs_memctx_fsp_extension(vfs_handle_struct *handle, files_struct *fsp);
 void *vfs_fetch_fsp_extension(vfs_handle_struct *handle, files_struct *fsp);
diff --git a/source3/include/smb.h b/source3/include/smb.h
index 3da63cfc2b..100ec21031 100644
--- a/source3/include/smb.h
+++ b/source3/include/smb.h
@@ -373,7 +373,9 @@ struct rpc_cli_smbd_conn;
 struct vfs_fsp_data {
     struct vfs_fsp_data *next;
     struct vfs_handle_struct *owner;
-    /* NOTE: This structure contains two pointers so that we can guarantee
+    void (*destroy)(void *p_data);
+    void *_dummy_;
+    /* NOTE: This structure contains four pointers so that we can guarantee
      * that the end of the structure is always both 4-byte and 8-byte aligned.
      */
 };
diff --git a/source3/include/vfs.h b/source3/include/vfs.h
index e9115ab807..228f090600 100644
--- a/source3/include/vfs.h
+++ b/source3/include/vfs.h
@@ -679,8 +679,8 @@ typedef struct vfs_statvfs_struct {
 /* Add a new FSP extension of the given type. Returns a pointer to the
  * extenstion data.
  */
-#define VFS_ADD_FSP_EXTENSION(handle, fsp, type) \
-    vfs_add_fsp_extension_notype(handle, (fsp), sizeof(type))
+#define VFS_ADD_FSP_EXTENSION(handle, fsp, type, destroy_fn)		\
+    vfs_add_fsp_extension_notype(handle, (fsp), sizeof(type), (destroy_fn))
 
 /* Return a pointer to the existing FSP extension data. */
 #define VFS_FETCH_FSP_EXTENSION(handle, fsp) \
diff --git a/source3/modules/vfs_cacheprime.c b/source3/modules/vfs_cacheprime.c
index fed051ca8d..71b850505a 100644
--- a/source3/modules/vfs_cacheprime.c
+++ b/source3/modules/vfs_cacheprime.c
@@ -54,7 +54,7 @@ static bool prime_cache(
         SMB_OFF_T * last;
         ssize_t nread;
 
-        last = (SMB_OFF_T *)VFS_ADD_FSP_EXTENSION(handle, fsp, SMB_OFF_T);
+        last = (SMB_OFF_T *)VFS_ADD_FSP_EXTENSION(handle, fsp, SMB_OFF_T, NULL);
         if (!last) {
                 return False;
         }
diff --git a/source3/modules/vfs_commit.c b/source3/modules/vfs_commit.c
index 1cef6d0243..a8105e021e 100644
--- a/source3/modules/vfs_commit.c
+++ b/source3/modules/vfs_commit.c
@@ -190,7 +190,7 @@ static int commit_open(
                                         MODULE, "eof mode", "none");
 
         if (dthresh > 0 || !strequal(eof_mode, "none")) {
-                c = VFS_ADD_FSP_EXTENSION(handle, fsp, struct commit_info);
+                c = VFS_ADD_FSP_EXTENSION(handle, fsp, struct commit_info, NULL);
                 /* Process main tunables */
                 if (c) {
                         c->dthresh = dthresh;
diff --git a/source3/modules/vfs_prealloc.c b/source3/modules/vfs_prealloc.c
index 5a339dbf8d..299f6548a1 100644
--- a/source3/modules/vfs_prealloc.c
+++ b/source3/modules/vfs_prealloc.c
@@ -164,7 +164,7 @@ static int prealloc_open(vfs_handle_struct* handle,
 	if ((flags & O_CREAT) || (flags & O_TRUNC)) {
 		SMB_OFF_T * psize;
 
-		psize = VFS_ADD_FSP_EXTENSION(handle, fsp, SMB_OFF_T);
+		psize = VFS_ADD_FSP_EXTENSION(handle, fsp, SMB_OFF_T, NULL);
 		if (psize == NULL || *psize == -1) {
 			return fd;
 		}
diff --git a/source3/modules/vfs_streams_xattr.c b/source3/modules/vfs_streams_xattr.c
index 37473439dd..77ffff5fb5 100644
--- a/source3/modules/vfs_streams_xattr.c
+++ b/source3/modules/vfs_streams_xattr.c
@@ -405,7 +405,8 @@ static int streams_xattr_open(vfs_handle_struct *handle,  const char *fname,
 	}
 
         sio = (struct stream_io *)VFS_ADD_FSP_EXTENSION(handle, fsp,
-							struct stream_io);
+							struct stream_io,
+							NULL);
         if (sio == NULL) {
                 errno = ENOMEM;
                 goto fail;
diff --git a/source3/smbd/vfs.c b/source3/smbd/vfs.c
index df5a39eea2..515e557f67 100644
--- a/source3/smbd/vfs.c
+++ b/source3/smbd/vfs.c
@@ -220,7 +220,9 @@ bool vfs_init_custom(connection_struct *conn, const char *vfs_object)
 
 #define EXT_DATA_AREA(e) ((uint8 *)(e) + sizeof(struct vfs_fsp_data))
 
-void *vfs_add_fsp_extension_notype(vfs_handle_struct *handle, files_struct *fsp, size_t ext_size)
+void *vfs_add_fsp_extension_notype(vfs_handle_struct *handle,
+				   files_struct *fsp, size_t ext_size,
+				   void (*destroy_fn)(void *p_data))
 {
 	struct vfs_fsp_data *ext;
 	void * ext_data;
@@ -238,6 +240,7 @@ void *vfs_add_fsp_extension_notype(vfs_handle_struct *handle, files_struct *fsp,
 
 	ext->owner = handle;
 	ext->next = fsp->vfs_extension;
+	ext->destroy = destroy_fn;
 	fsp->vfs_extension = ext;
 	return EXT_DATA_AREA(ext);
 }
@@ -256,6 +259,9 @@ void vfs_remove_fsp_extension(vfs_handle_struct *handle, files_struct *fsp)
 		    } else {
 			    fsp->vfs_extension = curr->next;
 		    }
+		    if (curr->destroy) {
+			    curr->destroy(EXT_DATA_AREA(curr));
+		    }
 		    TALLOC_FREE(curr);
 		    return;
 		}